#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
    int arr[10] = { 0 }, sum = 0;
    double average = sum / 5.0;
    int i = 0;
    while (i < 5)
        {
            scanf("%d", &arr[i]);
            i++;
            sum += &arr[i];
        }
    printf("%lf", average);
    return 0;
}